Gain Notes for Revolution 2682

No JEM-X2 science data for this revolution due to re-allocation of TM packets.

This revolution contains a TOO observation of Swift J1727.8-1613, a very
	strong blackhole source which caused extensive greyfiltering which 
	largely swamped and destroyed the Xe line.

At the same time the Sun, approaching Solar Max, was very active during
	this revolution (low latitude aurorae observed) and this has
	produced radical gain suppression, below 20 chans/keV which
	means all the low-level photons (about 5keV and below, depending
	on the exact value of the detector gain) will have disappeare into
	the low level discriminator - i.e. filtered out onboard as
	electronic noise. For this reason the entire revolution will be
	considered a BTI. Without this solar activity, the TOO observation
	alone would be the BTI. BTI = 8646.8 to 8649.2 IJD. This data
	is not suitable for spectra or low energy lightcurves. 

This is one of the later revolutions in the mission where the calibration
sources have become so weak that for the best energy determination an
IC Gain History table is needed. These gain history tables are found
automatically by OSA, or can be downloaded from the DTU FTP site.
 
All offline gain/energy corrections (including the IC tables) are based on the
two Fe calibration sources in JEM-X1, for both units, then corrected iteratively
using the instrument background lines (Xe, backed up by Cu and Mo).

Latest OSA software (version 10 and higher) automatically cuts out the first
Science windows of data from each revolution to ensure that people do not use data
from the instrument-settling period. This process can be overruled, but only by
experienced users.
	
JEM-X1 rating: Very good outside of the TOO observation, but whole revolution
	is declared at BTI due to the extreme gain suppression due to solar 
	activity that sends all the low-energy photons into the low-level
	discriminator to be discarded as electronic noise.  

JEM-X2: No data - TM packets allocated to SPI and IBIS. 

CAO 07/09/2023